I have every symptom that the original poster mentions except I am using mac ox sierra 10.12.3. I am using parallels running a windows 10 VM and the FTDI device that I'm using works fine there.

Since upgrading to OS X Sierra 10.12, I've started using PropellerIDE. (Thanks, Brett, Steve, and Parallax!) Initially I had a problem with the FTDI serial ports, including but not limited to the Prop Plug and my own FT231X boards. I hadn't seen this issue mentioned here and it took some hair tearing and googling to figure it out. The issue is that Apple, starting with OS X Mavericks (10.9), has included a driver for FTDI serial ports along with the system install.

If you then go and download install the FTDI version 2.3 VCP driver directly from FTDIchip.com, the two will conflict. The symptoms are that you will be able to use the port once, but then if you disconnect the dongle and then come back to it or try to use another one on the same USB port, you will find that it is locked. Alternative player to itunes for mac. The only way to get another try is to move to another physical USB port until that gets locks and so on.

If you look in the system report under USB, you will probably find that the same VCP serial port is listed twice. To fix this, delete the FTDI driver. Describes how. Delete it using Terminal from /Library/Extensions/FTDIUSBserialDriver.kext. Keep the Apple FTDI driver, which on Sierra is located at /System/Library/Extensions/AppleUSBFTDI.kext. The name and exact location of the Apple driver on pre-Sierra OS versions is different though. I see that the instructions on the Parallax web site page for PropellerIDE specifically recommend downloading the FTDI version of the driver.

That suggestion should probably be stricken or nuanced. Hi Tracy, This is a revisit of a long-time problem that, of course, started back with OSX Mavericks. For a long time we stopped including the FTDI drivers with the installers of certain Mac software because of the problems caused, ultimately, by Apple's supplied driver.

It sounds like I need to check this very carefully again (though I recall doing so with Sierra even) because Apple's driver for FTDI devices did not include support for DTR control; an important requirement for programing Propeller's and BASIC Stamps. In all my testing, I never found there to be a problem on my systems (old and new Mac OSXes) if the FTDI driver was installed, then the system was rebooted; however, based on your experience above, I'm compelled to retest those specific situations again.

I've also tried directly disabling Apple's 'FTDI' driver or FTDI's driver to see the effect. Our current releases of SimpleIDE and BlocklyPropClient includes the FTDI drivers, but also required a system restart after install to ensure that Apple's driver takes a 'back seat' to the FTDI driver, as Apple intentionally set theirs to a lower priority. When I get a chance to do this, I may be calling you to compare notes more in real-time.

Hi Jeff, Thanks for looking into it; what a mess! It looks like earlier versions of the Apple driver were crippled but have improved with with El Captan and Sierra.

The 3rd comment from 'armless' in link I posted above quotes FTDI tech support: Since 10.9 (Mavericks), OS X has included built-in partial support for some FTDI devices in VCP mode. Starting with 10.11 (El Capitan), Apple's own driver seems to be sufficiently comprehensive that many customers will not need to install FTDI's own VCP unless they wish to use its advanced features such as baud-rate aliasing and configurable latency times. My own experience is that the Apple driver does work to reset the Prop in Sierra for PropellerIDE once the doubles issue is resolved.

I was using bst in El Capitan, 10.11, after a jump direct from 10.6.8, and it was working, but I didn't keep careful track of anything special I did to tweak the system for the FTDI driver. I would say though it was flaky. Yesterday I built Yosemite 10.10 in a separate partition. But that is still not working, as in no DTR response. I tried renaming the Apple driver as.disabled and FTDI 2v3 installed, but that didn't work.